Still Banking on the Best

Merck & Co. Inc. isn't saying why it handed betrixaban back to Portola Pharmaceuticals Inc., but the biotech still believes the oral Factor Xa inhibitor has best-in-class potential. Portola thus plans to move the compound into Phase III testing itself, but in a smaller indication than it had hoped to pursue with Merck.

Betrixaban belongs to a new wave of anticoagulants designed to block one of two individual coagulation factors: either thrombin or Factor Xa. These compounds are intended to replace warfarin, which is widely used but carries a risk of major bleeding and has complicated dosing, unpredictable kinetics and interactions with many drugs and even food...